Method of making laminated pressure vessels



Dec. 26, 1944. c, GRUBB 2,365,696

METHOD OF MAKING LAMINATED PRESSURE VESSELS Filed Jan. 8, 1941 Fig Z 5 R 26 A B 28 42 44 U H M/22 Fig. 4 Fig 5 IN VENTOR C. Grubb John ATTORNEY.

Patented Dec. 26, 1944 METHOD OF MAKING LAMINATED PRESSURE VESSELS John C. Grubb, Barberton, Ohio, assignor to The Babcock & Wilcox Company, Newark, N. J a corporation of New Jersey Application January 8, 1941, Serial No. 373,560

2 Claims.

This invention relates to the method of making pressure vessels.

In many industries there has been considerable demand for pressure vessels to be used in manufactures involving corrosive fluid and high temperature and pressure conditions. In many cases pressure vessels of large size are required.

To meet such requirements, and more particularly the high pressures involved, pressure vessels must have steel walls of considerable thickness, such thicknesses often being greater than five inches.

The forming of such thick steel plates to a pressure vessel contour involves costly and time consuming operations, and the welding together of such formed plates not only involves extensive deposits of weld metal, but such welds are. in many cases, so deep, or thick, that they are beyond the economic, if not the effective range of X-ray apparatus employed in the examination of welds.

To construct such thick walled pressure vessels entirely of corrosion-resistant metals such as stainless steel would involve prohibitive costs.

To overcome these difficulties, the present invention presents a pressure vessel of laminated construction, the main body, or the cylindrical .portion of the vessel, comprising a plurality of contacting concentric shells. These shells are relatively thin and they are assembled tightly, one about another. Furthermore, the innermost shell may be of expensive and high quality corrosion-resistant metal such as stainless steel, while the tightly fitting outer shell or shells are of less costly steel, and are utilized to provide the pressure vessel with the proper hoop strength.

For high pressures the present invention contemplates a number of such concentric shells, constituting a pressure vessel body of considerable wall thickness. The illustrative pressure vessel heads are preferably unitary forgings of wall thickness of a similar order. It is contemplated that these heads shall be Welded to the ends of the laminated shell, and the invention involves an improved method of accomplishng such welding. It also provides a method of joining a plurality of laminae and a heavier plate.

According to prior art practices such welds would be formed by the deposition of Weld metal in the deep circumferential grooves formed by the ends of the laminated shell and the circumferential portions of the heads, and owing to the depth of such grooves excessive deposits of weld metal would be required. This would not only excessively increase the cost of manufacture, but in laminated shell constructions, it would involve a danger of cracks originating at the plate separations, or at the juncture of the shell laminae and the welds.

An objector the present invention is to overcome such difficulties and to eliminate such undesirable characteristics or contingencies.

The invention will be described with reference to preferred embodiments thereof which are shown in the accompanying drawing.

In the drawing:

Fig. 1 is a longitudmal section through a pressure vessel constructed in accordance with the teachings of this invention.

Fig. 2 is a detail section showing an illustrative junction of the pressure vessel head and th laminated shell.

Fig. 3 is a detail view of the type of Fig. 2, but illustrating another embodiment; and

Figs. 4 and 5 are sectional views illustratin other modifications in which the laminae of a pressure vessel shell are united with pressure vessel heads.

The heads I!) and II of the illustrative pressure vessel are preferably unitary steel bodies forged to the conformation shown. After forging, the ring faces of the heads are machined so as to give them the stepped construction illustrated. This construction may be considered as involving a plurality of weld annuli, or annular formations such as those indicated by A,B--C-D, C-E-F, and F--G-H, in Figs. 2 and 3, similar formations also being involved in the embodiments shown in Figs. 4

and 5. 1

In the construction shown the corrosion-resistant shell, or innerilamina of the entire shell is of an inside diameter corresponding with the inside diameter of the annular formation A--BCD of the pressure vessel heads. This shell is constructed by the bending of a plate to a hollow cylindrical form and then welding together its confronting edges. Thereafter, it is aligned with the pressure vessel heads [0 and H arranged relative thereto to form such weld grooves as that indicated at A-DJ--K in Figs. 2 and 3.

The next step in the illustrative method is deposition of the weld metal 26 in the weld groove AD-J-K. This may be accomplished by fusion welding involving the deposition of weld metal under the protection of a flux, and the illustrative method has the advantage that this initial weld is well within the effective range of X-ray equipment utilized for weld examination. Such equipment may be employed after the weld metal 26 is deposited, and after any adhering flux covering is removed.

In Fig. 2, the external surface of the weld 26 is aligned with circumferential surface D-C of the stepped construction of the head l0.

After the weld 26 is completed and examined, and its exterior surface is treated in the manner described, the filler ring 2M, preferably of tapered cross-section as shown, is tightly fitted over the weld 26 so as to completely separate that weld from successive and separately formed welds. One of the latter, the weld 28 is then made in the same manner as the weld 2B, the filler ring 20 being thus joined to the head annulus C-E-F.

The next step in the illustrative method is to form the steel shell or lamina l4 tightly around the inner shell or lamina l2. The shell I4 is preferably formed in a manner similar to the manner in which shell l2 was formed, but the former is shorter as indicated in Figs. 1 and 2, and its end is spaced from the filler ring 20 so as to present the weld groove R-S-T-U. Welds 30 and 3|, similar to the previously formed weld 26 are then formed, and the shell l4 thus is effectively united with the head H.

The Figs. 1 and 2 of the drawing show a third lamina or shell IS in stepped relation to the inner-lamina or shell l4 and united with the heads l and II in a manner similar to that by which the shell I4 is joined to those heads. The filler ring I 8 is first placed so as to cover and extend beyond the ring 20 and its joining welds 2! and 30. Thereafter the weld 22 is formed,' 1oinlng the head I 0 with the filler ring, and then the latter is joined with the shell It by the formation of the weld 24. v

In the manufacture of the particular pressure vessel structure illustrated in Figs. 1 and 2 of the drawing the entire shell construction may be made up as a separate body before either one of its component shells are Joined to the heads l0 and II, but in the embodiment illustrated in Fig. 3 of the drawing the different shells or laminae 4042 must be successively formed. In other words, the inner-shell "is formed and united with the head H by the weld 44 and then the succeeding shell 4| is formed around the inner-shell with its end extending over the weld 44 so as to separate the subsequently formed weld 45 from the weld 44.

In the embodiments indicated in Figs. 4 and 5 of the drawing, a greater number of thinner shell laminae are involved, and each annular weld portion of the stepped part of the head is joined with a plurality of the laminae. Referring to Fig. 4, the inner sub-shell or cylindrical lamina B2 is first united with the head 48 by the deposition of weld metal which may constitute part of the weld 48, the remainder of this weld subsequently Joining the lamina 84 to the same weld annulus of the head. Thereafter, the filler ring 58 is fitted over the top surface of the weld 48 and united with the next outer weld annulus of the drum 46 by weld M. Then the shell laminae 88 and 88 are successively welded to the filler ring 58, these laminae being shown as secured to this filler ring by the weld "L The structure indicated in Fig. 4 is completed by the positioning of the filler ring 00 over the welds 50 and 58 and the filler ring 58, the formation of the weld 52, and the successive welding of the shell laminae HI and 12 to the filler ring III.

In the embodiment of the invention illustrated in Fig. 5 of the drawing, the separately formed welds l4, l5 and 18 each unite a plurality of shell laminae directly with the head 46. Each of these welds may be formed in successive welding operations. For example, a part of the weld 14 may be deposited to unite the lamina In with the head 46 and then the remainder of this weld formed to unite the lamina 82 with the head. Similarly, the laminae 84 and 88 may be united with the next outer step of the head and then the outermost laminae 88 and 90 joined with the head by successive deposits of parts of the weld 18.

While the invention has been described with reference to the details of the preferred embodiments, it is to be appreciated that the invention is not limited to all those details. It is rather to be taken of such a scope that it may be utilized with various combinations of those details, within the scope of the subioined claims.

I claim:

1. In a method of fabricating pressure vessels of the laminated shell type, forming unitary pressure vessel heads with concentric annular weld annuli presenting stepped ring face formations forming a cylindrical inner shell component, presenting a circumferential weld groove by juxtaposing the inner shell component in alignment with an inner weld annulus of corresponding diameter, depositing weld metal in said groove and fusion uniting the head and said shell component in a unitary'structure, forming a separate circumferential weld groove separated and spaced substantially from the first by interposed shell metal by juxtaposing a concentric shell component relative to another weld annulus, simultaneously causing one shell to overlap the other in a direction endwise of the vessel, and utilizing the fusion of welding in said spaced groove to unite the other shell component with said head without interfusion or contact between the metals of the separate welds.

2. The method of fabricating a pressure vessel of the laminated shell type; the method comprising the steps of: forming and welding plate metal to form a hollow cylindrical shell; circumferentially shouldering the axial face of a pressure vessel head to present inner and outer weld annuli of different diameters; presenting a circumferential weld groove by juxtaposing said shell in alignment with and axially spaced from said inner annulus; depositing weld metal in said groove to fusionally unite said shell and the inner weld annuli of the head; tightly fitting a second shell about the first shell with the second shell in alignment with and spaced from an outer weld annulus to form a second weld groove; simultaneously covering or overlapping said weld metal with said second shell so that the second weld groove is substantially spaced and separated from the fused metal of the first weld; and depositing weld metal in said second groove to fusionally unite said second shell and the outer weld annuli without lnterfusion of the metal fused in the first weld and that fused in the succeeding weld.

JOHN c. (moan. 

